Method of continuously quenching molten metal coatings

ABSTRACT

A WIRE PASSING UPWARDLY AFTER HAVING PASSED THROUGH A MOLTEN METAL COATING BATH IS CONTACTED WITH A MOVING STREAM OF WATER JETTING UPWARDLY THROUGH THE ATMOSPHERE AT AN ANGLE. THE STREAM OF WATER AND THE MOVING WIRE MEET JUST AT THE APEX OF THE STREAM WHERE THE ENERGY OF MOVEMENT OF THE WATER IS LEAST. THE COOLING STREAM OF WATER THUS CAUSES A MINIMUM DISTURBANCE OF THE STILL MOLTEN COATING ON THE WIRE.

July 3, 1973 G. PADJEN ET AL 3,743,535

METHOD OF CONTINUOUSLY QUENCHING MOLTEN METAL COATINGS Filed Dec. 28,1971 United States Patent O M 3,743,535 METHOD OF CONTINUUSLY QUENCHINGMOLTEN METAL COATINGS George Padjen and Joseph A. Brugger, Bethlehem,Pa., assignors to Bethlehem Steel Corporation Filed Dec. 28, 1971, Ser.No. 213,143 Int. Cl. C23c 1/00 U.S. Cl. 117-114 R 7 Claims ABSTRACT OFTHE DISCLOSURE BACKGROUND -O'F THE -INVENTION The present inventionrelates generally to the quenching of coated wire and other linearmaterial and more particularly to the quenching with a fluid coolingmedium of a molten metallic coating on a moving continuously coated wireor the like.

lIt is frequently desirable to cool or quench a moving length of linearmaterial such as wire or narrow strip passing upwardly out of a moltenbath of coating metal such as molten zinc, aluminum or copper. Promptquenching of the linear material is frequently important in order toretard the development of an interfacial alloy layer between the coatingmetal and the base metal or to solidify the coating metal promptly sothat it can be contacted with a guide sheave or the like either tochange the direction of the linear material or to damp vibrations in thewire.

If linear material is contacted with any sort of guide pror tosubstantial solidiiication of a recently applied molten coating upon thesurface, the still molten coating would be marred by the contact, evenwhere the guide only gently contacts, or kisses, the linear material.`On the other hand a molten coating metal deposited upon a moving wireor strip will frequently take a signicant period to solidify in ambientshop conditions and if the linear material is moving at a fair speed itcan travel long distances before solidiication occurs. This longdistance is usually arranged to be in a vertical direction upwardly fromthe coating pot so that the molten metal will not be differentiallyaffected by gravity. The long unsupported length of linear material may,however, be subject to rather severe `vibration which frequently willcause lumpy and/ or eccentric coatings.

Various quenching means have been used to quench a still molten coatingwithout marring the surface of the coating. In general these quenchingdevices have involved either blasts of a gas such as air, tine mists ofa fluid cooling medium such as water, ne sprays of water or the like orin some cases quenching vin a tank of cooling fluid. In general each ofthese prior devices has suffered from some serious drawbacks eitherbecause the cooling action afforded was insuicient or the physicaldisturbance of the coating by the quenching means was too great.

SUMMARY OF THE INVENTION The aforesaid difficulties of the prior art inquenching still molten coatings on moving linear material have now beenobviated by the present invention. In accordance with the presentinvention a coated wire, narrow strip or other linear material passingfrom a molten coating 'bath or other means for applying a molten coatingis quenched 3,743,535 Patented July 3, 1973 ICC by contacting thecoating with a moving stream or streams of an upwardly directed coolingfluid, or liquid, at the apex of the upward movement of such stream orstreams. The stream or streams of cooling uid are generally in the formof a fountain of iluid similar to the stream in a drinking fountain. Theupwardly directed component of motion of the stream of liquid is justbarely exhausted at the apex of movement of the said fountain typestream so that there is at this point an absolute minimum of movement inthe stream of liquid to disturb the still molten coating on the Wirewhile at the same time the cooling liquid contacting the coating iscontinuously renewed at a rapid rate with fresh cooling liquid to mostefficiently quench the coating. Since the upward component of motion ofthe stream is then exhausted, the only movement of the cooling liquid atthe apex is whatever horizontal component of movement the liquid has.This horizontal component can be made as small as desired depending uponwhere the exhausted liquid is desired to impinge as it descends from theapex of its trajectory and the resulting contact of the cooling tiuidwith the object being cooled and the coating on it can be adjusted to beonly the barest touch while still renewing large quantities of coolingliquid next to the coated surface. The moving liquid thus achieves whathas been termed laminar oW cooling but with only very gentle contact onthe piece being quenched.

BRIEF DESCRIPTION OF THE DRAWING FIG. l is a schematic representation ofa portion of a coating line incorporating the quench arrangement of thepresent invention.

FIG. 2 is a enlarged sectional view of the quenching device of theinvention.

|FIG. 3 is a plan view of FIG. 2 at 3 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. l a wire 11 passes froma pretreatment apparatus 13 which may frequently be a preheating furnacebut which may also be a cleaning apparatus or flux applying apparatus.As the wire 11 leaves the pretreatment apparatus 13 it passes over guidesheave 15 which directs the wire downwardly into a molten metal coatingbath 17 containing a molten coating metal such as aluminum, zinc orcopper. The molten metal comprising bath 17 is contained in a moltenmetal coating pot 19. Wire 11 passes downwardly under sinker roll 21submerged under the surface of the bath 17 and then upwardly out of themolten bath 17 to dancer roll 23 where the wire 11 changes direction andpasses downwardly under guide sheave 25 which directs the wire away fromthe coating pot 19 to some other treatment or coiling operation, notshown. The distance from the surface of the molten bath 17 to the dancerroll 23 is frequently substantial to allow time for the molten coatingto solidify before contacting the roll 23. In order to cause acceleratedsolidification of the molten coating on the wire 11 after it leaves thebath 17, so that the wire may be contacted with a vibration dampingcontact roll 27 and also to decrease the growth of an interfacial allo-ylayer between the coating metal and the underlying base metal of thewire-if such an interfacial alloy tends to form between the base metaland the particular coating metal-the wire 11 rst passes through a lightforced air stream from dual nozzles 29 and 31 connected by header 33 toa source of compressed air, not shown. A valve 35 in the header 33 maybe used to regulate the flow of air from nozzles 29 and 31 so that theforced air flow is sufficient to just cool the surface of the coating.Such air ow may be adequate to place a very thin solied shell of coatingmetal over the surface but should not be sufficient to otherwise disturbthe surface. The wire 11 next immediately passes to a fountain typequench apparatus 37 where the surface of the coating is quickly cooledbelow the solidification point and the entire wire is subjected toaccelerated cooling by a laminar flow of a cooling liquid such as waterpast and around the surface of the wire.

The quench apparatus 37 is constructed as shown best in FIGS. 2 and 3 sothat a series of discrete streams or jets of water 53 and 55 areprojected upwardly at an angle calculated to intersect with the upwardpath of the wire or wires 11 just as the upward movement of the saidstreams or jets of coolant has reached its highest point or elevation.The stream of diowing water thus has a bare minimum of motion when itintersects the wire 11 and only a very gentle contact with the surfaceof the coating takes place. The coolant water, however, is still quicklyremoved, or moved past the wire, so that a good laminar iiow typecooling of the molten metal coating on the wire is attained.

lIn the quench apparatus 3,7 cooling water from an external source, notshown, enters the apparatus from a main header '39 regulated by a valve41. From the main header 39 the water enters two vertically disposeddescending headers 43 and 45 and a cross over or connecting header 47.Spaced at intervals along the descending headers 43 and 45 are upwardlyinclined cooling nozzles 49 and 51, respectively, positioned at anglessuch that a stream or jet of water 53 and 5S issuing from each of thenozzles 49* and 51 respectively intersects the wire 11 at the apex ofthe stream and then falls in a descending arc downwardly into sumps 57and 59 in the bottom of the casing 61 of the quench apparatus 3'7.Drains 63 and 65 connect with a main 67 and serve to remove the waterfrom the various streams from the sumps l5-7 and 59.

As seen in FIG. 2 the two sets of nozzles 49 and 51 are positioned upontheir respective descending headers 43 and 45 so that the streams orfountains of water 5'3 and '55 issuing from them intersect the wire 11at different levels to prevent the splashing which would otherwise takeplace if several streams intersected the wire at the same point. As seenin FIG. `3 the nozzles are also positioned so that the streams orfountains 53` and 55 do not impinge upon the opposing headers or nozzlesas the streams fall into the sumps 57 and 59. FIG. 3 also shows thatmore than one wire 11 may be passed through the quench apparatus andcooled without interference with adjoining fountains or streams ofcoolant. It will be understood that in FIGS. 1 and 2 additional wires 11passing through the apparatus may be hidden behind the wire 11 visiblein the respective views. In FIG. 3 duplicate numbers are used toidentify duplicate headers and nozzles used to apply cooling streams toadditional wires 11.

Since practically all of the cooling water from each of the nozzles 49and 51 passes freely around and past the wire 11 and continues in moreor less discrete streams into the sumps 57 and 59, it will be seen thatvery little water is left over to run down the wire or wires 11 into thecoating pot 19. Likewise there is very little splashing caused by thewire or wires passing through the apex of each cooling stream of water.Any water which clings to the wire is drawn upwardly and away with themoving wires and is also usually rapidly evaporated from the stillrelatively hot surface of the wire. The fountain type quench of theinvention is, therefore, particularly suitable for placement directlyover a molten coating bath where any substantial dripping or splashingof water or other cooling liquid upon the bath would be intolerable.This is an important advantage since it is usually advantageous to passa wire or other elongated material vertically up from a molten bathuntil the outer coating solidies in order that the molten coating willnot be differentially affected by gravity. The quench apparatus of theinstant invention can. be placed on the vertical run of the linearmaterial from the bath without any significant moisture escapingdownwardly from the apparatus even though there are no seals around thewires. (Seals might damage the still molten coating.) A relatively largeentrance orifice 69 may thus be provided in the bottom of the apparatusequal or even greater in size than the exit orifice 71 for the linearmaterial positioned in the top 73 of the apparatus.

The use of the initial gentle blast or iiow of cooling air directed uponthe linear material from nozzles 29 and 31, while very desirable priorto passage of the wire through the fountain type quench of theinvention, is by no means necessary for use with the quench if the airis not desired. The cooling air stream from the air nozzles 29 and 31will tend to form a very thin skin or incipient skin of solidifiedcoating material upon the surface of the wire which skin, when the wirepasses through the fountain type quench, is just sufficient to preventany disturbance at all of the surface of the still unsolidified coatingas it passes through the apex of the stream of coolant in the fountainquench apparatus. The combined use of the forced air cooling followedimmediately by the fountain type quench of the invention is particularlyeffective and desirable if there is a fair component of horizontalmovement of the coolant streams at the apex of said streams. On theother hand, however, it is by no means necessary to use the initialforced air cooling prior to quenching, particularly if the angle of thestreams of coolant is arranged so that the horizontal component ofmotion is minimal at the apex of said streams, or if a very minor ornegligible disturbance of the coating surface is not regarded asseriously detrimental.

It is likewise not always necessary to use the vibration damping contactroll 27 with the quench apparatus 37. The dancer roll 23 can instead bemoved down closer to the coating pot 19 to replace the damping roll 27if vibration damping is desired, or if vibration is not deemedimportant, and quenching is accomplished in the particular operationmerely to decrease interface alloy formation, the dancer roll 23 may beleft in the same position. The use of the additional vibration damperroll 27, which may be adjusted by suitable biasing mechanism to justkiss the wire after the quench, is particularly effective and desirable,however.

We claim:

1. A method of quickly cooling moving linear material having a moltenlayer of coating metal upon its surface without marring or otherwisephysically disturbing the surface of said molten metal coatingcomprising:

(a) directing a jet of cooling liquid upwardly at an angle, and

(b) intersecting said jet of cooling liquid at the apex of its freeupward movement with the path of the moving linear material.

2. A method of cooling linear material according to claim 1 wherein thelinear material consecutively intersects a plurality of jets of linearmaterial spaced lengthwise along its line of travel.

3. A method of cooling linear material according to claim 2 wherein thesurface of the molten metal coating on the linear material is contactedwith a forced air stream prior to intersection of said linear materialwith said jet of cooling fluid.

4. A method for suppressing vibrations of wire passing from a moltencoating bath after being coated comprising:

(a) passing the wire substantially vertically upwardly from the surfaceof a molten metal coating bath,

(b) establishing a jet of fluid cooling material passing upwardly at anangle inclined from the vertical,

(c) intersecting the fluid jet at its apex with the path of the wire tocool the molten coating with a laminar flow of cooling liquid, and

(d) contacting the cooled surface of the wire with a vibration dampingmeans subsequent to passage through said cooling liquid.

l5. A method for suppressing vibration of wire according to claim 3wherein the wire is contacted with a forced air stream between thesurface of the molten coating bath and the jet of cooling auid of (b).

6. A method for suppressing vibrations of wire according to claim 5wherein the cooling uid is water.

7. A method for suppressing vibrations of wire according to claim 6wherein the wire passes consecutively through a plurality of jets ofcooling fluid.

References Cited UNITED STATES PATENTS 2,166,249 7/1939 Herman 117-128 X2,266,322 12/1941 Jominy 73-15.4 2,588,439 3/1952 Ward 117-119.4 X

6 2,732,319 1/1956 Cree 117-119.4 2,914,419 11/1959 Oganowski 117-114 AX 2,950,991 8/ 1960 Seymour 117--128 X 3,148,080 9/1964 Mayhew 117-114 AX 3,148,081 9/1964 Ross 117-114 A X 3,235,960 2/ 1966 Carreker, Jr.117-114 R UX 3,260,577 7/1966 Mayhew 117-114 A X 3,369,923 2/1968Laidman 117-114 A X ALFRED L. LEAVTIT, Primary Examiner J. R. BA'I'I'EN,JR., Assistant Examiner U.S. Cl. X.R.

117-114 A, 114 B, 114C, 119.4, 128; 118-63, 69; 134-64

